The present disclosure generally relates to food technologies. More specifically, the present disclosure relates to direct-cryogen injection cooling devices comprising a double-helical (e.g., s-shaped) coil, a backpressure valve, and a helical (e.g., circular) coil, wherein the devices allow for maximum heat extraction from a heated food product using a direct-injected liquid cryogen, followed by a complete separation of the gaseous cryogen phase from the cooled food product, while avoiding the formation of a stable foam.
An example of a direct-cryogen injection cooling device is the Nitrogen Injection System manufactured by Pick Heaters, Inc. of West Bend, Wis. The Nitrogen Injection System (“NIS”) is essentially a modification of the traditional direct steam injection (“DSI”) system that is widely utilized throughout the food processing industry. According to the design of the DSI system, a multiple orifice steam injector (with hundreds of small orifices), in conjunction with a helical-flights mixer, ensures intimate blending of the steam and the product, resulting in 100% heat transfer. By comparison, the NIS by Pick Heaters, Inc. utilizes the same mechanical design, as the one described for the DSI system, whereby a liquid-nitrogen stream now is supplied to the multiple orifice injector, instead of steam.
Another example of a direct-cryogen injection cooling device is disclosed in European Patent Application EP 1 734 320 to Rosenbaum et al. (“Rosenbaum”). Rosenbaum relates to a continuous process for rapid cooling of a flowable material by mixing the material with a liquid cryogen, while the material and the cryogen flow through an inline continuous mechanical mixer. The discharge from the inline continuous mechanical mixer may flow into a product receiver to disengage and exhaust the gaseous cryogen from the cooled product. The inline continuous mechanical mixer may operate at rotational speeds of 400-2000 RPM.
There exists a need for an energy efficient direct-cryogen injection cooling device that is able to maximize heat extraction from a heated food product using a direct-injected liquid cryogen and to provide a complete separation of the gaseous cryogen phase from the cooled food product, while avoiding the formation of a stable foam.